1. Technical Field
This invention relates to an improved potato planter, and more particularly, to a potato planter which utilizes pairs of interfitting, rotating augers to form traveling compartments within the auger housing to meter the flow of potato seed pieces from the hopper to the discharge chute.
2. Background Art
Tuber potatoes are one of the more sophisticated row crop plants grown in the United States of America. There is a wide variety of potatoes grown in various locations across the North American Continent. For purposes of illustration in the background section, the Russet Burbank potato, which is grown across the state of Idaho and in eastern portions of the states of Washington and Oregon, will be used.
The intended end use of the potato crop will determine the size of the potatoes desired from any particular growing field. If the intended end use of potatoes is processing into french fries, then it is desirable to produce the largest possible potatoes in that particular field. If, on the other hand, the intended use of the potatoes is to be fresh packed and sold as fresh produce or as baking potatoes, then a smaller size is desired.
Aside from extreme abnormal weather conditions which can obviously affect size and quantity of a potato crop, the dominant factor in determining the end size of the crop is the spacing of the seed at the time of planting. For example, with the Russet Burbank potato variety a nine inch spacing between seed and rows 36 inches apart will produce potatoes suitable for fresh pack produce and sale as baking potatoes. On the other hand, spacing of the same potato seed 14 inches apart in the same rows 36 inches apart will produce fewer, but much larger potatoes suitable for processing into frozen french fries.
Potatoes are also one of the more expensive crops to grow. Current practice today requires extensive cultivation, usually accomplished by means of aerial applications of chemicals, and the use of expensive and sophisticated harvesting and handling equipment to prevent bruising or damage to the harvested crop. In today's competitive agricultural market, it is therefore critical to the farmer that the entire field be completely planted with potato seed, each set at the desired spacing interval along each row.
Potato seed, as a general rule, is grown in special disease free regions in carefully monitored disease free fields. It is desirable that the seed potatoes be smaller than standard production crops grown for human consumption. And, like standard potato crops, the size of the seed is determined by the interval spacing of the seed potato in the rows of the field. Potato seed is notoriously expensive and its waste by over planting in the field is an unnecessary expense to the commercial farmer. In connection with this, it has been known for many years that it is not necessary to plant an entire potato as seed for a single potato plant. All that is required for seed is a piece of a seed potato containing one potato eye. Therefore, it is common practice to cut seed potatoes into pieces prior to planting.
This creates another set of problems in that the potato seed is not round or of any uniform shape. Generally, it is hemispherical in shape, with a significant portion being cylindrical or even oblong. Therefore, a pile of potato seed such as that contained in a planter hopper, does not flow as well as, for example, grain or corn seed would. The pieces of potato seed have a tendency to interlock and bridge forming a structural mass.
As a result, the farmer desiring to plant potato seed is faced with three problems, the first is to how to get the interlocked and bridged seed out of the hopper and into the ground, the second, how to minimize the transmission of disease from a diseased piece of seed potato to other seed potatoes given the fact that significant portions of the cut seed pieces are not covered by the protective potato skin, and third, how to insure that there are no skips in the planting process, that is to say that there is a potato seed placed every 9 inches or every 14 inches or whatever the desired interval may be, and finally, how to prevent the waste of seed by the planting of doubles. That is to say two or more pieces of potato at each spacing interval instead of just one. Each of these problems has significant financial consequences to the farmer. The costs to the farmer of growing and harvesting a field planted at an 85% capacity rate is exactly the same as that for the same field planted at 100% of its capacity. Thus, whatever the skip rate is in planting, translates directly into a loss of profits. A field planted to 105% of its capacity due to double planting translates into an increased seed cost which also results in a loss of profits. And finally, transmission of diseases such as leaf ring virus through the seed results in discolored potatoes and a significant decrease in their market value.
Hand planting of potato seed is not feasible given the enormous acreages planted each year. Standard planting equipment such as grain drills for wheat and corn cannot be used since the potato seed does not flow due to its shape. As a result, potato planters all have a common conceptual basis in that some sort of mechanism is used to pick individual pieces of potato out of the hopper then transport and drop it into a furrow being plowed in the row or hill, after which the furrow is covered leaving the potato seed piece in the ground approximately 2 to 4 inches below the surface.
Two common methods of picking the potato seed pieces from the hopper are in use today. Perhaps the most common is the use of the spiked wheel which is shown in FIG. 1 and identified as prior art. With this method, a wheel having radial spokes with spikes emanating therefrom is rotated beneath the hopper, where the spikes impale pieces of potato which are gravity fed into the wheel chamber from the hopper. A cam mechanism is provided within the wheel assembly to withdraw the spikes from the radial spokes as the wheel rotates to drop the potato seed piece into a discharge chute. The problems with this type of potato planter are twofold. First, diseases are easily transmitted from one piece of potato seed to another compounding any problem with a small percentage of the seed which may be diseased when planted. Secondly, this type of planting mechanism has a tendency, by its design, to produce skips in the rows of seed potatoes.
A second mechanism commonly in use to retrieve seed potato from the hopper is the use of seed cups on a traveling conveyor belt. This type of mechanism is shown and described in CURL, U.S. Pat. No. 3,982,671. While this type of cup mechanism reduces the transmission of disease, in that the seed pieces are not impaled upon a common spike, it has the propensity to plant doubles since the cups will often pick up two pieces of potato seed instead of just one.
Accordingly, what is needed is a mechanism by which seed can be retrieved from the hopper and transported to the discharge chute without impalement of the seed pieces. Another object of the invention is to provide for a transport mechanism which does not skip or double plant the seed pieces in the rows of planted crop.